Aromatics oxidative ring cleavage

On the other hand, aromatic nitro compounds having either lowest (n,7t )-or (7r,7i )-triplets are able to induce oxidative ring cleavage of aromatic methoxy compounds 65-67) a. typical example is given below. 

Tetracyanoethylene oxide [3189-43-3] (8), oxiranetetracarbonitnle, is the most notable member of the class of oxacyanocarbons (57). It is made by treating TCNE with hydrogen peroxide in acetonitrile. In reactions unprecedented for olefin oxides, it adds to olefins to form 2,2,5,5-tetracyanotetrahydrofuran [3041-31-4] in the case of ethylene, acetylenes, and aromatic hydrocarbons via cleavage of the ring C—C bond. The benzene adduct (9) is 3t ,7t -dihydro-l,l,3,3-phthalantetracarbonitrile [3041-36-9], C22HgN O. 

While oxidation of p-coumaric acid was occurring, the major intermediates formed are p-hydroxybenzaldehyde and p-hydroxybenzoic acid. Low concentrated aromatic intermediates such as phenol and p-hydroxybenzyl alcohol and traces of hydroxylation products such as, 3,4- dihydroxybenzaldehyde and 3,4-dihydroxybenzoic acid were detected. Furthermore, formic and oxalic acids were the ring-cleavage compounds detected. 

Figure 5. The enzymatic oxidation of a synthetic / -0-4 lignin model substrate and fungal secondary metabolites. Both undergo Ca-C/ bond and aromatic ring cleavages in reactions catalyzed by the same ligninase in the presence of H2O2.

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